Long stroke horizontal type air compressor



Sept. 6, 1938.

W. B. HALE LONG STROKE HORIZONTAL TYPE AIR COMPRESSOR Filed March 17, 1936 3 Sheets-Sheet l J5 IIVENTOR.

1 ATTORNEYS w. B. HALE 2,128,937

LONG- S'I'ROKE HORIZONTAL TYPE AIR COMPRESSOR Filed March 17, 1936 3 Sheets-Sheet 2 A'r'roRNEYs Sept. 6, 1938. w. B. HALE 2,128,937

LONG STROKE HORIZONTAL TYPE AIR COMPRESSOR Fil ed March 17, 1956 s Sheets-Sheet 5 v 59 40 41 h V 6 n :n m 1 rrk-fiTn PM kuxm v" Patented Sept. 6, 1938 UNITED STATES PATENT OFFICE LONG STROKE HORIZONTAL TYPE AIR COMPRESSOR vada Application March 17, 1936, Serial No. 69,312

15 Claims.

This invention relates to gas compressors, and while the invention may be embodied in machines for compressing gases for any purpose whatever, in the present specification the invention is described as applied to an air compressor, and particularly to a multiple-stage or two-stage compressor of the reciprocating type.

Most compressors of the reciprocating type operate at high piston speed, and have a relatively short stroke. As there is a limit to speed at which air will flow into the compression cylinder, due to the high speed of the piston there is insufficient time permitted for the cylinder to receive a full charge of air at atmospheric pressure .before the piston commences its return stroke to compress the charge. This occasions a loss in efiiciency. Furthermore, air in being compressed becomes heated, and in a high speed compressor very little time elapses in each compression stroke, so that there is little time for the air being compressed to be cooled. In the operation of two-stage or multiple-stage compressors heretofore, it has been the practice to provide inter-coolers for cooling the air between the compression stages, and this is usually accomplished by circulating the air through metal coils such as copper coils surrounded with circulating water.

One of the objects of the present invention is to provide a gas compressor or air compressor of simple construction, having a relatively long stroke as compared with the diameter of the cylinder in which the gas or air is compressed, and capable .of operating at a relatively slow piston 35 speed, allowing more time to be consumed on the intake stroke of the piston, to the end that the cylinder will be fully charged with air at substantially atmospheric pressure before the compression stroke begins.

Furthermore, compressors of the reciprocating type that operate at a relatively high piston speed, have a relatively low efiiciency due to the relatively great number of strokes of the piston, for the reason that the effects of the fraction representing the volumetric efficiency becomes J multiplied. One of the objects of this invention is to produce a compressor of this type that will overcome this objection.

A further object of the invention is to provide simple means for cooling the compression cylinders, and for cooling the air between the compression stages without necessitating the use of circulating water, or fan.

In its preferred construction the compressor ;)5 involves the use of two oppositely disposed aligned cylinders, and these cylinders are preferably of difierent diameters, the larger cylinder being employed in the first-stage of the compression, while the smaller cylinder is employed in the second stage. Between these cylinders a long-stroke chain drive is employed with means for driving the chain through the medium of a small motor such as an electric motor. One of the objects of the invention is to provide simple means for mounting the endless chain or chains of the drivingapparatus for reciprocating the cross-head to which the piston rods are attached, and to provide simple means for enabling adjustments of the standards or bearings for the sprocket wheels that support the chains, to be effected.

The compressor is preferably of the horizontal type, the cross-head being provided with a vertical slot which is driven by a wrist carried on the endless chain drive; and one of the objects of the invention is to provide an improved construction for the driving wrist of the cross-head, and improved means for connecting it to the driving chains.

A further object of the invention is to improve the general construction of two-stage air compressors of a horizontal reciprocating type.

' Further objects of the invention will appear hereinafter.

The invention consists in the novel parts and combination of parts to be described hereinafter, all of which contribute to produce an efficient long stroke horizontal type air compressor.

A preferred embodiment of the invention is described in the following specification, while the broad scope of the invention is pointed out in the appended claims.

In the drawings:

Figure l is a side elevation of an air compressor embodying my invention, and also illustrating the air tank connected up to the compressor to be charged with air.

Fig. 2 is a plan of the compressor illustrated in Fig. 1, but with the motor omitted.

' Fig. 3 is a vertical section through the compressor taken about on the line 3-3 of Fig. 4.

Fig. 4 is a horizontal section taken through the compressor on the line 44 of Fig. 3; in this view certain parts are broken away, and the intercooler is represented also in longitudinal section.

Fig. 5 is a vertical cross-section taken about on the line 55 of Fig. 3 but upon an enlarged scale, and particularly illustrating the mounting for the driving mechanism of the compressor.

Fig. 6 is a side elevation of the assembly of parts to be connected as one piece, into the endless chain or chains of the compressor, for driving the crosshead.

Fig. 7 is a cross-section taken on the line T| of Fig. 6, and further illustrating details of the construction of this Wrist. This view also shows the flanged roller sleeve in cross-section, which is carried by the wrist. This roller sleeve is omitted in Fig. 6.

Fig. 8 is a fragmentary vertical section taken about on the line 88 of Fig. 3, and further illustrating details of the means for mounting the adjustable standards that support the endless chains.

Fig. 9 is an end view of the parts shown in Fig. 6, that is to say it shows the end of the driving wrist and short portions of the driving chain broken away.

Referring more particularly to the parts, and especially to Fig. 1, l indicates a tank about which a rudimentary frame 2 is built, said frame supporting a compressor 3.

The casing of the compressor preferably includes a central box-form body 4 through which .a countershaft 5 extends, said countershaft being provided on one end outside of the casing with a pulley or sprocket wheel 5 driven by a belt or sprocket chain 7 which, in turn is driven by the pulley or sprocket wheel 8 on the shaft 9 of a motor Ill, preferably an electric motor.

The box-form body 5 of the casing preferably has vertical end walls I i and i2, which have openings l3 in them, which operate as seats for the inner ends of the compression cylinders 14 and l5, the former of which is of relatively large diameter, and is the first-stage cylinder, while the latter is of relatively small diameter and is the second-stage cylinder. In these cylinders pistons 16 and if reciprocate, said cylinders being connected by a piston rod formed in sections Ilaand lib, which connect up to a cross-head l8, said cross-head being preferably constructed of two oppositely disposed yokes with flanges i9 that are bolted together, and these yokes cooperate to form a vertical guide slot 20 for connection to the driving means to reciprocate the pistons.

The construction for reciprocating the pistons, preferably includes an endless drive chain device including two oppositely disposed endless chains 2!, which, toward the high pressure end of the compressor are carried on two assemblies of sprocket wheel and shaft including sprocket wheels 22, and horizontal shafts 23, and these shafts are mounted in two standards or bearings 24, each of these standards or bearings preferably comprising two upwardly extending posts 25. The sprocket shafts 23 are preferably mounted in ball bearings 26 Within the posts, and each sprocket shaft carries a rigid gear wheel or pinion 21 held between the standards of the corresponding standard bearing. Above the sprocket shafts 23 the aforesaid countershaft 5 extends through the standard bearings, but only through the outer posts of the same (see Fig. 5) This countershaft 5 projects at one side so as to carry a fly wheel 28,

and within the chamber 29 that is formed in the box-form housing or body 4, a countershaft is provided with driving pinions 30 that mesh with the gears 21 to drive the sprocket wheels 22 and thereby drive the chains 2 l Adjacent the other end of the chamber 29 and in line with the main standards 2 a similar pair of standard bearings 3! are provided, which standards are also preferably formed with two standards or posts 32, which carry bearings for the shafts 33 of sprocket wheels 34 that carry the sprocket chains 2|. The standard bearings 24 are preferably held in a fixedposition while the standards 31 are preferably mounted for adjustment to enable the slack of the chains- 2! to be taken up as the same become stretched. All of the standard bearings are supported on a base plate 35 that forms the bottom for the central chamber 29, and

in order to hold the standard bearings securely in position, their bottom faces 36 are provided with grooves 31 that engage over a longitudinal key 38, which is set in the upper side of the base plate (see Fig. 5). The standards 25 have flat upper faces 39 that rest against the under face of the cover plate 40 of the chamber 29, so that when this cover plate is clamped down by means of bolts 4i, these standards will be held securely in posi tion.

The adjustable standards 3|, however, are capable of sliding on the guide tongues or keys 38, and in order to enable them to be adjusted toward or from the fixed standards 24, their upper ends are provided with bolts 42 that extend down through slots 43 formed in the cover plate, so that when the cover plate is bolted down the standard will be clamped between the base plate 35 and the cover. Clamping bolts 45 are provided in the base plate 35, that pass down through slots 45a in the bases 46 of the standards 3|, being received in threaded openings 46a, in the base plate 35, (see Fig. 5).

The base plate 35 may be provided with four feet or legs 48 that may be secured by bolts to the upper side bars of the frame 2 (see Fig. 1).

Pistons l5 and IT are preferably provided with substantially gas-tight rings 59, and are preferably mounted for adjustment on the ends of the piston rod sections Ila and Nb. For this purpose the ends of these rods have threaded necks 5| of reduced diameter, received in threaded openings in the pistons, and the pistons can be clamped rigidly in any adjusted position desired, by means of set screws 52.

The cylinder I4 is provided at its outer end with a low pressure cylinder head 53 provided with an inlet 54 for admitting the gas or air that is to be compressed. This head is formed with a transverse web 55 that divides its interior into an inlet valve chamber 56 and an outlet valve chamber 51, and these chambers are provided with an inlet valve 58 and an outlet valve 59 respectively. These valves are preferably of the poppet type with springs as illustrated.

The outer end of the high pressure cylinder I5 is provided with a suitable high pressure head 60,

and this head is divided by a central web similar to the web 55 into an inlet valve chamber BI and an outlet valve chamber 62, said chambers being provided with suitable inlet and outlet valves 63 and 64 of the same type as: those at the low pressure end of the compressor.

The gas or air compressed by the low pressure piston I6 is expelled through an outlet pipe 65, which is preferably connected to an inter-cooler 66 to cool the air between the stages of compression. This inter-cooler is constructed so that the air passing into the inter-cooler cools itself by expansion. And the inter-cooler is preferably constructed so that the warm compressed air from the first-stage cylinder may be expanded one or more times to cool it. For this purpose the inter-cooler is preferably constructed of a plurality of sections 66a, 66b, 66c and 66d, each of these sections being composed of a plurality of laterally expanded heads forming cooling expan- 75 for the passage of the air or gas.

superficial area of the cylinder.

sioncham'bers 61 'with a relatively large superficial area exposed to the atmosphere. The expanded cooling heads are connected by .necks 88 of reduced diameter, and through these sections 66a, 6%, etc., openings '69 are formed These openings 89 are of substantially the same diameter, but the opening 666 where the air passes from the section 86a into the section 66b is of relatively small diameter; for example, three-eighths of an inch, and as the air flows through this opening, the opening acts as an expansion nozzle, that is to say, the air of relatively high pressure in the section 66a expands through this opening into the section 561), thereby cooling this air by its expansion. From the section 66b the air flows through another expansion opening 66f of relatively small diameter but slightly larger than the opening 881;; for example, fiveeighths of an inch. And as the air expands through this opening into the section 660, it cools itself further by expansion. In the present instance no further expansion is provided for, but in practice, another expansion opening may be provided between the section 660 and section 66d. In this way the air may be cooled by successive expansions and contractions. From the last section 66d the air passes out through a pipe connection 69a that connects to the interior of a cooling jacket 18 of cylindrical form that surrounds the high pressure cylinder l5 forming a :ooling space H of relatively large volume through which the air passes, and the wall of this cylinder is provided with a plurality of outwardly projecting fins or ribs 12, which greatly increase the In the present instance, the air from the inter-cooler is passed first to the cooling space H around the high pressure cylinder, and the inter-cooler extends longitudinally of the cylinders, being supported at its ends on the piping 65 and 69a.

From the cooling space H the air passes by a suitable pipe connection 13 to a cooling space 14, of relatively large volume, which surrounds the low pressure cylinder I4, then to the cooling jacket 15, which is similar to the jacket 18 and spaced a considerable distance from the cylinder wall. This provides a relatively large space for expansion. The cylinder wall for this cylinderis also preferably provided with outwardly projecting ribs or fins 16 to increase its superficial area.

The pipe 13 preferably connects to the cooling space 14 toward the outer end of the cylinder, and. at the inner end of the cylinder jacket 15 a pipe connection 1'! leads off to the high pressure end of the compressor where it admits the air or gas for compression, to the inlet chamber 6| of the high pressure head 60. The outlet valve chamber 62 is connected by a suitable pipe connection 18 to the tank I already referred toin connection with Fig. 1.

Each of the sprocket chains 2| preferably comprises oppositely disposed outside links 19 (see Fig. 7) and inside links 88, said links being connected together by pins-8| with rollers 82 mounted on the pins between the inside links.

In order to reciprocate the cross-head I8, the chains 2| are connected by a driving wrist 83 (see Fig. 5) and this wrist is in the form ofa cylindrical block, the body of which carries a sleeve or roller 84, the diameter of which fits neatly into the slot 28, and the ends of this roller or sleeve 84 are provided with flanges 85 that project over the edges of the slot 28. The ends of the wrist 83 are cut awaysoasito form a recess 86 at each end, and to form outside connecting links to be connected into the chain. These recesses are respectively in line with the chains 2|. Beyond each recess the wrist is formed with a projecting link 81 that extends down across the 5' plane of the run of the chain, and the body of the wrist is provided with two longitudinally disposed pins 88 that extend through the same, which are preferably of substantially the same diameter as the pins 8| of the chain. These pins 88 have a '10 driving fit in the wrist 83, and their ends extend across the recesses 88 and into the links 81. Each link 81 is of substantially the same length as the outside links 19 of the chain. The chain is connected so that two inside links are placed on 15 the inner side of the tongue links 81 wherethe pin is connected into the chain (see Fig. '7). The chain has the usual anti-friction rollers 82. In this way the driving wrist 83 for the cross-head is connected into the chain, so that its connection 0 with the chain operates substantially like. one of the links of the chain, performing the functions of the outside links, where it is connected into the chain.

In order to support the cross-head l8 in its travel to and fro between the adjacent open ends of the cylinders I4 and I5, I prefer to provide guideways 92 (see Figs. 4 and 5) that extend longitudinally in the central chamber 29, and which are secured to the base plate 35. A cross- *3 head engages the inner and adjacent faces of these guide rails 92, and is provided on its side faces with longitudinal grooves 93 that receive guide bars 94 that are bolted to the upper faces of the guide rails 92. If it is desired, the motor 85 I8 may be mounted so as to provide a take-up adjustment for insuring that the driving belt or chain 1 from the motor to the countershaft 5 will be sufficiently tight. For this purpose the cover plate 4|] may be provided with a slide plate i 48a that rests on it, and which is connected to the cover plate 48 by bolts 95 running through slots 96 in the slide plate a, and the slide plate may be provided with upwardly projecting lugs 91, which are engaged by set screws '98 mounted in lugs 99 cast integral with the cover plate 48. Evidently by loosening the bolts 95 the slide plate 40a can be adjusted by tightening up the set screws 98, after which the bolts 95 can be tightened up. Pads or seats 49 for the legs of the motor are carried on the slide plate 48a.

The general mode of operation of the compressor will now be described.

Through the driving belt or chain 1 the countershaft 5 is continuously rotated, thereby enabling the driving pinions 38 to rotate the gear wheels 21, and these gear wheels being rigid with the sprocket shafts 23, drive the sprockets 22, which in turn drive the chains 2|. The driving wrist 83 carried by the chains, of course, as it travels longitudinally along the axis of the cylinders, will cause the cross-head 18 to reciprocate, thereby reciprocating the piston heads l6 and II. On each intake stroke of the low pressure cylinder 18, gas or air will pass in the inlet 54, pass the inlet valve 58 and enter the cylinder. On each outstroke this valve will close, and the outlet valve'58 open so as to permit the compressed air to pass out through the pipe connection into the .intercooler 66. At this point the air is cooled sufficiently to enable it to be employed'for cooling the wall of the high pressure cylinder I5 .when this air passes through the jacket space H surrounding this cylinder. From this point thegas or'air passes through the. low .pressurejacket space 34,

through which it flows to cool the wall of the low pressure cylinder. From this point the gas or compressed air passes through the pipe connection I! to the inlet chamber 6! of the high pressure cylinder head 60, and from this point the partially compressed air passes into the high pressure cylinder [5 on each in-stroke of this piston. The motor should drive the chain at sufficient speed to give about to strokes of the piston per minute, depending of course, largely upon the duty of the compressor.

By adjusting the positions of the pistons on the rods, they can be positioned so that at the end of the out-stroke they will lie very close to the inner face of their corresponding heads. For this reason the volumetric efiiciency of the cylinders is very high, as there is substantially no clearance space. In this connection it should be noted that the valves are placed in the heads so that the inner faces of the valves are substantially flush with the inner faces of the heads, in accordance with the usual practice where such valves are placed in compressor heads.

The efficiency of this compressor will be evident from the following considerations: At the end of each compression stroke of a piston a small quantity of compressed air is left in the end of the cylinder, and hence the greater the number of strokes the piston makes, the greater will be the loss due to the volume of air remaining in the cylinder. The cylinders of my compressor, due to the construction I employ, have very high volumetric efiiciency; and on account of the fact that relatively few strokes occur in compressing the air, the efliciency of the compressor is very high as compared with that of ordinary reciprocating compressors.

The central chamber 29 is preferably filled with lubricating oil, which covers the driving chains and the cross-head, thereby lubricating the driving chain of the pins and its contacts with the cross-head. Furthermore, this oil passes into the open ends of the cylinders hi and I5, and maintains the walls of these cylinders very effectively lubricated to reduce the friction of the pistons l6 and IT.

When it is necessary to take up slack in the driving chains 2|, this of course, is accomplished by loosening up the nuts 44 that attach to the upper ends of the adjustable standards 31, and also loosening up the set screws 45, whereupon these standards can be moved toward the right, as viewed in Fig. 3, to take up the slack of the chains.

As the jacket spaces H and M are of relatively large volume, the air expands as it is forced into them, thereby cooling the air in the jacket spaces by its own expansion, and cooling the cylinder walls.

It is understood that the embodiment of the invention described herein is only one of the many embodiments this invention may take, and I do not wish to be limited in the practice of the invention, nor in the claims, to the particular embodiment set forth.

What I claim is:

1. In a gas compressor, tne combination of a pair of coaxial long-stroke horizontal cylinders arranged in tandem and disposed apart, a pair of endless chains mounted to run longitudinally with the cylinders, located between the same, and on opposite sides of the axis of the cylinders, piston heads in the cylinders respectively, operating to compress the gas in the cylinders ends, said pistons having a piston rod connecting the same and lying between the chains, said rod having a cross-head; and a driving wrist driven by the chain and engaging the cross-head for reciprocating the same, and means for driving the end less chains, said chain operating to give the piston rod relatively few strokes for a given volume of gas compressed, and thereby reducing the clearance losses during compression of a given volume of gas.

2. In a two-stage gas compressor, the combination of a pair of coaxial long-stroke horizontal cylinders arranged in tandem and disposed apart, one of said cylinders being of relatively large diameter, and the other of said cylinders being of a relatively small diameter, a pair of endless chains mounted to run longitudinally with the cylinders between the same, said chains located respectively on opposite sides of the axis of said cylinders, piston heads in the cylinders respectively operating to compress the gas in the cylinder ends, said pistons having a piston rod connecting the same and lying between the chains, said rod having a cross-head, and a driving wrist carried by the chain and engaging the cross-head for reciprocating the same, means for driving the endless chains, said chain operating to give the piston rod relatively few strokes for a given volume of gas compressed, and thereby reducing the clearance losses during compression of a given volume of gas, an inlet valve for admitting the gas to be compressed at the outer end of the cylinder of relatively large diameter, an outlet valve located at the outer end of the same cylinder, an inter-cooler receiving the compressed air from the outlet valve having a relatively large radiating surface for cooling the gas by expansion and contraction, cooling jackets of relatively large volume respectively surrounding the cylinders, and means connecting the inter-cooler with the cooling jackets for circulating the cooled air through the same, and permitting the air to expand in the cooling jackets.

3. In a two-stage gas compressor, the combination of a pair of long-stroke coaxial horizontal cylinders arranged in tandem and disposed apart, one of said cylinders being of a relatively large diameter, and the other of said cylinders being of a relatively small diameter, a pair of endless chains mounted to run longitudinally with the cylinders between the same, located respectively on opposite sides of the axis of the cylinders piston heads in the cylinders respectively operating to compress the gas in the cylinder ends, said pistons having a piston rod connecting the same lying between the chains, said rod having a crosshead, and a driving wrist carried by the chain and engaging the cross-head for reciprocating the same, means for driving the endless chains, said chain operating to give the piston rod relatively few strokes for a given volume of gas compressed, and thereby reducing the clearance losses during compression of a given volume of gas, a cylinder head with an inlet valve for admitting the gas to be compressed at the outer end of the cylinder of relatively large diameter, an outlet valve located in the said head and receiving air through the inner face of the head, an inter-cooler receiving the compressed air from the outlet valve having a relatively large radiating surface for cooling the gas by the atmosphere, and by expansion and contraction, cooling jackets respectively, surrounding the cylinders, means connecting the inter-cooler with the cooling jackets for circulating the cooled air through the same, and means for controlling flow of cooled gas thereafter into the cylinder of relatively small diamincluding a low pressure cylinder and a high pressure cylinder, a cylinder head corresponding to each cylinder on the outer ends thereof, an endless chain mounted to run longitudinally of the cylinders between the same, piston heads in the cylinders, respectively, with a piston rod connecting the piston heads; said rod having a cross-head, a driving wrist driven by the chain engaging the cross-head for reciprocating the same, means for driving the endless chain, each of said cylinder heads having an inlet valve and an outlet valve for the gas, an intercooler extending longitudinally with the cylinders and connected with the low pressure cylinder head to receive gas from the same for cooling the gas, a cooling jacket surrounding the high pressure cylinder and receiving the cooled gas from the inter-cooler, a cooling jacket surrounding the low pressure cylinder with means for passing the gas from the cooling jacket of the high pressure cylinder, through the cooling jacket of the low pressure cylinder, and means for delivering the gas from the cooling jacket of the low pressure cylinder tothe cylinder head of the high pressure cylinder for compressing the gas in the high pressure cylinder.

5. In a gascompressor, the combination of a casing having a central chamber with oppositely disposed substantially vertical end walls having aligning openings therein forming cylinder seats, coaxial cylinders mounted in said cylinder seats and open at their inner ends, piston heads for compressing the gas in the cylinders mounted to reciprocate in the cylinders, a piston rod connecting the same, with a cross-head located in the said central chamber, a pair of endless chains mounted to run longitudinally with the cylinders in the said chamber, located respectively on opposite sides of the axis of the cylinders, a driving wrist carried by the chain and engaging the cross-head for reciprocating the same, means for driving the endless chains, and cylinder heads on the outer ends of the cylinders with inlet and outlet ports and valves therein respectively for the cylinders, said ports passing through the inner face of the cylinder heads.

6. In a gas compressor, the combination of a casing having a central chamber with oppositely disposed substantially vertical end walls having aligning openings therein forming cylinder seats, coaxial cylinders mounted in said cylinder seats and open at their inner ends, piston heads mounted to reciprocate in the cylinders for compressing the gas in the cylinders, a piston rod connecting the same, with a cross-head located in the said central chamber, a pair of endless chains mounted to run longitudinally with the cylinders in the said chamber, located respectively on opposite sides of the piston rod, a driving wrist carried by the chains and engaging the cross-head for reciprocating the same, means for driving the endless chains, cylinder heads on the outer ends of the cylinders with inlet and outlet valves therein respectively for the cylinders, the ports for said valves passing through the inner faces of said cylinder heads, one of the cylinders being of relatively large diameter and constituting the low pressure first-stage compression cylinder,

and the other of said cylinders being of relatively small diameter and constituting a high pressure second stage compression cylinder, and an inter-cooler for receiving the compressed gas from the low pressure cylinder, with means connected therewith for delivering the gas from the inter-cooler to the high pressure cylinder for compression therein.

7. A two-stage gas compressor constructed as described in claim 4, in which the inter-cooler is formed with expansion chambers in which the compressed gas from the first stage is expanded, thereby developing a cooling effect.

'8. In a gas compressor, the combination of a casing having a central chamber with oppositely disposed end walls having aligning openings therein forming cylinder seats, cylinders mounted in said cylinder seats and open at their inner ends, piston heads mounted to reciprocate in the cylinders, a piston rod connecting the same with a cross-head located in the said central chamber, a pair of oppositely disposed endless chains extending longitudinally with the axes of the cylinders and located in the said chamber, a pair of pillow blocks mounted in said chamber adjacent one end of the same, sprocket wheels rotatably mounted in said pillow blocks with spooket wheels carrying the endless chains respectively, a second pair of pillow blocks mounted in the said chamber adjacent the other end thereof, means for supporting the same for adjustment toward or from the first named pillow blocks, a cover plate seating on the upper side of the casing and covering the said chamber, means on the outer side of the cover for clamping the second-named pillow blocks and enabling the last-named pillow blocks to be adjusted toward or from the first-named pillow blocks and secured in a fixed position with respect to the same, sprocket wheels rotatably mounted in the second-named pillowblocks with sprocket wheels for carrying the said chains, a wrist connecting the said chains and engaging the cross-head for reciprocating the piston rod.

9. A gas compressor constructed as described in claim -8, in which the said clamping means for the second-named pillow blocks includes slots formed in the cover plate, and clamping bolts passing through the slots and mounted in the upper ends of the second-named pillow blocks for securing the same.

10. In a gas compressor, the combination of a casing having a central chamber with oppositely disposed end walls having, aligning openings therein forming cylinder seats, cylinders mounted in said cylinder seats and open at their inner ends, piston heads mountedto reciprocate in the cylinders, a piston rod connecting the same with a cross-head located in the said central chamber, a pair of oppositely disposed endless chains extending longitudinally in the said chamber, abase plate forming the bottom for the said chamber, a pair of oppositely disposed pillow blocks supported on the base plate adjacent one end of the said chamber, each of said pillow blocks comprising two upwardly extending standards, a sprocket wheel corresponding to each pillow block carrying one of said endless chains and having a stub shaft rotatably mounted in the standards of its corresponding pillow block, a gear wheel carried rigidly by each stub shaft between the standards of its corresponding pillow block, a transverse countershaft located above the gear Wheels and having driving gear wheels meshing with the first named gear Wheels for driving the chains, a second pair of pillow blocks supported on the base plate adjacent the other end of said chamber, sprocket wheels rotatably supported in the second-named pillow blocks and carrying the said chains, means for guiding the second-named pillow blocks longitudinally of the chains, means for securing the second-named pillow blocks in a fixed position, and a wrist carried by the said chains and engaging the said crosshead for reciprocating the piston rod.

11. In a gas compressor, the combination of a casing having a central chamber with oppositely disposed end walls having aligning openings therein forming cylinder seats, cylinders mounted in said cylinder seats and open at their inner ends, piston heads mounted to reciprocate in the cylinders, a piston rod connecting the same with a cross-head located in the said central chamber, a pair of oppositely disposed endless chains mounted to run longitudinally with the cylinders in the said chamber, a driving wrist connecting the said endless chains, said driving wrist consisting of a cylindrical block having recesses out in the ends thereof in line with the said chains respectively and secured to the said chains, said cross-head having a substantially vertical slot receiving the body of said wrist between said chains for, reciprocating the cross head.

12. In a gas compressor, the combination of a casing having a central chamber with oppositely disposed substantially vertical end walls having aligning openings therein forming cylinder seats, cylinders mounted in said cylinder seats and open at their inner ends, piston heads mounted to reciprocate in the cylinders, a piston rod connecting the same with a cross-head located in the said central chamber, a pair of endless chains mounted to run longitudinally with the cylinders in the said chamber, sprocket wheels supported in the chamber for supporting the chains, a wrist connecting the said chains, said cross-head having a substantially vertical slot for receiving the said wrist to reciprocate the piston rods, said wrist consisting of a cylindrical block with recesses out in the ends thereof in line with the chains, a pair of pins extending longitudinally through the said wrist between the said recesses, the links of the chain adjacent said pins having bushings through which the ends of the said pins pass so that the ends of the said wrist operate as links in the said endless chains.

13. In a gas compressor, the combination of a casing having a central chamber with oppositely disposed substantially vertical end walls having aligning openings therein forming cylinder seats, cylinders mounted in said cylinder seats and open at their inner ends, piston heads mounted to reciprocate in the cylinders, a piston rod connecting the same with a cross-head located in the said central chamber, a pair of endless chains mounted to run longitudinally with the cylinders in the said chamber, sprocket wheels supported in the chamber for supporting the chains, a wrist connecting the said chains, said cross-head having a substantially vertical slot for receiving the said wrist to reciprocate the piston rods, said wrist consisting of a cylindrical block with recesses cut in the ends thereof in line with the chains, a pair of pins extending longitudinally through the said wrist between the said recesses extending into the recessesand se cured at their outer ends to a link of the chain adjacent each recess, and a flanged roller sleeve fitting over the body of the wrist and engaging the edges of the said slot.

14. A two-stage gas compressor constructed as described in claim 4, in which the inter-cooler consists of a plurality of connected sections, each section having a plurality of laterally expanded chambers therein with reduced necks connecting the same, said inter-cooler being provided with an expansion opening of reduced area whereby the compressed gas in passing through the intercooler expands intoithe expanded chambers and thereby reduces its own temperature.

15. In a two-stage gas compressor, the combination of a pair of long-stroke horizontal cylinders arranged in tandem and disposed apart, including a low pressure cylinder and a high pressure cylinder, a cylinder head corresponding to each cylinder on the outer ends thereof, an endless chain mounted to run longitudinally of the cylinders between the same, piston heads in the cylinders respectively with a piston rod connecting the piston heads, said rod having a cross head, a driving wrist driven by the chain engaging' the cross head for reciprocating the same, means for :driving the endless chain, each of said cylinder heads having an inlet valve and an outlet valve for' the gas, an inter-cooler for receiving the gas compressed in the lowpressure cylinder, said inter-cooler having an expansion chamber for the gas with an expansion opening through which the gasflows in passing into the expansion chamber whereby the gas reduces its own temperature by its expansion in the expansion chamr ber, and means for admitting the gas from the expansion chamber thereafter into the high pressure cylinder to compress the same through the second stage.

, WILLIAM B. HALE. 

